Ultra-wide input power supply

Abstract

A power supply circuit includes a supply input including a positive terminal, a neutral terminal, and a negative terminal, wherein an input voltage is applied to the positive terminal and the negative terminal; a first switching converter circuit referenced to the neutral terminal and having a first converter input coupled to the positive terminal, and a first converter output to produce a first regulated output voltage referenced to an isolated ground electrically isolated from the supply input; a second switching converter circuit having a second converter input coupled to the neutral terminal and the negative bus terminal, and a second switching converter circuit referenced to the negative terminal and having a second converter input coupled to the neutral terminal, and a second converter output to produce a second regulated output voltage referenced to the isolated ground.

What is claimed is: 
     
         1 . A power supply circuit comprising:
 a supply input including a positive terminal, a neutral terminal, and a negative terminal, wherein an input voltage is applied to the positive terminal and the negative terminal;   a first switching converter circuit referenced to the neutral terminal and having a first converter input coupled to the positive terminal, and a first converter output to produce a first regulated output voltage referenced to an isolated ground electrically isolated from the supply input; and   a second switching converter circuit referenced to the negative terminal and having a second converter input coupled to the neutral terminal, and a second converter output to produce a second regulated output voltage referenced to the isolated ground.   
     
     
         2 . The power supply circuit of  claim 1 , wherein the first and second switching converter circuits produce a regulated output voltage using a supply input voltage range that is more than fifty times greater than the regulated output voltage. 
     
     
         3 . The power supply circuit of  claim 1 , including:
 a first lockout circuit and a second lockout circuit;   wherein the first switching converter circuit includes the first lockout circuit and a first pulse width modulation (PWM) circuit to control switching of the first switching converter circuit;   wherein the second switching converter circuit includes the second lockout circuit and a second PWM circuit to control switching of the second switching converter circuit; and   wherein the first and second lockout circuits are configured to prevent startup of the PWM circuit of its respective switching converter circuit up to a startup threshold voltage level, above which the lockout circuit of the respective switching converter circuit turns off to enable the PWM circuit of the respective switching converter circuit to startup.   
     
     
         4 . The power supply circuit of  claim 1 , wherein the first and second switching converter circuits each produce a regulated output voltage from an input voltage ranging from a startup threshold voltage to a full range voltage and each switching converter circuit includes:
 a transformer including a primary side coupled to the switching circuit and a secondary side;   two cascode-connected field effect transistors (cascode FETs) connected to the primary side of the transformer, wherein the two cascode FETs include a top FET and a bottom FET; and   wherein the top FET is biased so that the bottom FET switches the input voltage when the input voltage is between the startup threshold voltage and one-half of a full range voltage, and both the top FET and bottom FET switch the input voltage when the input voltage is from one-half of the full range voltage to the full range voltage.   
     
     
         5 . The power supply circuit of  claim 4 , including:
 an FET bias circuit configured to bias the top FET circuit to turn on when the input voltage is between the startup threshold voltage and one-half of a full range voltage.   
     
     
         6 . The power supply circuit of  claim 1 , including:
 a first transformer to electrically isolate the first converter output from the positive terminal;   a second transformer to electrically isolate the second converter output from the neutral terminal; and   wherein the first and second transformers provide isolation of a secondary circuit side from a primary circuit side having an input range that is greater than fifty times the regulated output voltage of the respective switching converter circuit.   
     
     
         7 . The power supply circuit of  claim 1 ,
 wherein the first and second switching converter circuits have a flyback converter circuit topology; and   wherein each of the flyback converter circuits is configured to produce a regulated output voltage from an input voltage range that includes the regulated output voltage and a full range voltage that is greater than fifty times the regulated output voltage.   
     
     
         8 . A method of operating a power supply circuit, the method comprising:
 receiving a bus voltage at a positive terminal and a negative terminal of a supply input of the power supply circuit;   applying a first input voltage of the positive terminal to a first switching converter circuit referenced to a neutral terminal to produce a first regulated output voltage referenced to an isolated ground isolated from the supply input; and   applying a second input voltage of the neutral terminal to a second switching converter circuit to referenced to the negative terminal to produce a second regulated output voltage referenced to the isolated ground.   
     
     
         9 . The method of  claim 8 ,
 wherein the applying the first input voltage includes applying a first input voltage to the first switching converter circuit that is included in a voltage range from the first regulated output voltage to a voltage more than fifty times greater than the first regulated output voltage; and   wherein the applying the second input voltage includes applying a second input voltage to the second switching converter circuit that is included in a voltage range from the second regulated output voltage to a voltage more than fifty times greater than the second regulated output voltage.   
     
     
         10 . The method of  claim 8 , including:
 preventing startup of the first switching converter circuit until the first input voltage reaches a startup threshold voltage; and   preventing startup of the second switching converter circuit until the second input voltage reaches the startup threshold voltage.   
     
     
         11 . The method of  claim 8 , including:
 starting the first and second switching converter circuits when the bus voltage exceeds a high voltage detection threshold voltage level; and   activating an indicator circuit operatively coupled to the power supply circuit when the bus voltage exceeds a high voltage detection threshold voltage level.   
     
     
         12 . The method of  claim 8 , including:
 switching a bottom field effect transistor (FET) of a pair of cascode connected FETs of a switching converter circuit of the first and second switching converter circuits to produce a regulated voltage when the bus voltage is less than one half of a full range voltage level of the bus voltage; and   switching the bottom FET and a top FET of the pair of cascode connected FETs to produce the regulated voltage when the bus voltage is greater than one half of the full range voltage level of the bus voltage.   
     
     
         13 . A diagnostic system for an electric work machine, the system comprising:
 a direct current (DC) power bus to provide power to the electric work machine, the DC power bus including a positive DC bus connection and a negative DC bus connection;   a diagnostic circuit configured to monitor a bus voltage of the DC power bus, the diagnostic circuit including:   a power supply circuit including:   a supply input including a positive terminal operatively coupled to the positive DC bus connection, a negative terminal coupled to the negative DC bus connection, and a neutral terminal;   a first switching converter circuit referenced to the neutral terminal, and having a first converter input coupled to the positive bus terminal and a first converter output to produce a first regulated output voltage referenced to an isolated ground electrically isolated from the supply input; and   a second switching converter circuit referenced to the negative terminal, and having a second converter input coupled to the neutral terminal and a second converter output to produce a second regulated output voltage referenced to the isolated ground.   
     
     
         14 . The system of  claim 13 ,
 wherein the diagnostic circuit includes a first indicator circuit and a second indicator circuit; and   wherein the first converter circuit produces a first regulated output for the first indicator circuit, and the second converter circuit produces a second regulated output for the second indicator circuit.   
     
     
         15 . The system of  claim 14 ,
 wherein a voltage on the DC power bus is a DC operating voltage of the electric work machine; and   wherein the first and second indicator circuits include a lamp circuit, and the power supply circuit activates the lamp circuits when the DC operating voltage of the electric work machine exceeds a specified threshold voltage level.   
     
     
         16 . The system of  claim 13 , wherein the power supply circuit includes:
 a first transformer to electrically isolate the first converter output from the positive bus terminal;   a second transformer to electrically isolate the second converter circuit from the neutral bus terminal; and   wherein an input range of the DC operating voltage is from the first and second regulated output voltages to a full range voltage greater than fifty times the regulated output voltages.   
     
     
         17 . The system of  claim 13 ,
 wherein the first switching converter circuit includes a first lockout circuit and a first pulse width modulation (PWM) circuit to control switching of the first switching converter circuit;   wherein the second switching converter circuit includes a second lockout circuit and a second PWM circuit to control switching of the second switching converter circuit; and   wherein the first and second lockout circuits are configured to prevent startup of a corresponding PWM circuit until a voltage on the DC power bus increases to a startup threshold voltage level.   
     
     
         18 . The system of  claim 17 , wherein the startup threshold voltage level is a high voltage detection threshold level, and the supply output activates the indicator circuit when the voltage on the DC power bus increases to the high voltage detection threshold level. 
     
     
         19 . The system of  claim 13 , wherein the first and switching converter circuits each produce a regulated output voltage from an input voltage ranging from a startup threshold voltage to a full range voltage and each include:
 a transformer including a primary side coupled to the switching circuit and a secondary side;   two cascode-connected field effect transistors (cascode FETs) connected to the primary side of the transformer, wherein the two cascode FETs include a top FET and a bottom FET; and   an FET bias circuit configured to bias the top FET so that the bottom FET switches the input voltage when the input voltage is between the startup threshold voltage and one-half of a full range voltage, and both the top FET and bottom FET switch the input voltage when the input voltage is from one-half of the full range voltage to the full range voltage.   
     
     
         20 . The system of  claim 13 ,
 wherein the first and second switching converter circuits have a flyback converter circuit topology; and   wherein each of the flyback converter circuits is configured to produce a regulated output voltage from a voltage level of the DC power bus that is in a range of the first and second regulated output voltages to a voltage greater than fifty times the first and second regulated output voltages.